# std::swap(std::valarray)

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< cpp‎ | numeric‎ | valarray

Defined in header `<valarray>` |  |
template< class T > void swap( std::valarray<T>& lhs, std::valarray<T>& rhs ) noexcept; |  | (since C++11)

Specializes the std::swap algorithm for std::valarray. Swaps the contents of lhs and rhs. Calls lhs.swap(rhs).

### Parameters

lhs, rhs | - | valarrays whose contents to swap

### Return value

(none)

### Complexity

Constant.

### Example

Run this code

    #include <iostream>
    #include <valarray>

    void print(auto rem, const std::valarray<int>& v)
    {
        std::cout << rem << '{';
        for (char sep[]{0, ' ', 0}; auto elem : v)
            std::cout << sep << elem, *sep = ',';
        std::cout << "}\n";
    }

    int main()
    {
        std::valarray x{3, 1, 4, 1, 5};
        std::valarray y{2, 7, 1, 8};

        print("Before swap:\n" "x: ", x);
        print("y: ", y);

        std::swap(x, y);

        print("After swap:\n" "x: ", x);
        print("y: ", y);
    }

Output:

    Before swap:
    x: {3, 1, 4, 1, 5}
    y: {2, 7, 1, 8}
    After swap:
    x: {2, 7, 1, 8}
    y: {3, 1, 4, 1, 5}

### See also

swap | swaps with another valarray (public member function)

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